The row has been the main strain in ties between the world's top two nuclear powers and looms over the first face-to-face talks between new Secretary of State Colin Powell and Russian Foreign Minister Igor Ivanov, due on Feb. 24.
U.S. Defense Secretary Donald Rumsfeld fired his latest salvo Wednesday, saying Russia was "part of the problem" in missile technology proliferation, which has made the United States want to build a National Missile Defense (NMD).
Last week, Central Intelligence Agency director George Tenet said in testimony to Congress that Russia was one of the world's top three suppliers of weapons technology, with Russian entities providing "a variety of ballistic missile-related goods and technical know-how to countries such as Iran, India, China, and Libya."
Tenet also infuriated Russia by listing it as one of several global threats to the United States.
Russia's armed forces First Deputy Chief of Staff Valery Manilov was quick to respond to Rumsfeld's comments.
"These words are on the conscience of Mr. Rumsfeld as one can only make such statements when one has the necessary and incontrovertible proof of what the politician is saying.
"Russia has not violated, does not violate and will not violate its obligations, including in the area of non-proliferation," Manilov said.
Foreign Ministry spokesman Alexander Yakovenko, in comments officially issued by his office, sounded more cautious.
"As far as worries expressed by Mr. Rumsfeld are concerned, there is an appropriate Russian-U.S. mechanism of consultations which has existed for several years to deal with them," he said. "In our opinion it is hardly worth reducing such serious issues to exchanging 'propaganda shots' using the mass media."
But Moscow fears its own missiles could be shot down, which would weaken its nuclear deterrent, violate arms treaties and spark a new arms race that would suck in China.
Russia also says the U.S. project threatens international stability because it violates the 1972 Anti-Ballistic Missile (ABM) treaty. That treaty prohibits anti-missile systems that defend an entire nation.
President Vladimir Putin has called for Europe and the United States to work with Russia on deploying regional systems near rogue states' borders to shoot down missiles shortly after launch. But he has given few details, and Washington has been cool to the proposal.
But Washington's European partners in NATO, who also have reservations about NMD, have expressed more interest.
American proponents argue a national missile defense is needed to stop a missile carrying nuclear, biological or chemical weapons from hitting the United States. Rogue countries or terrorist groups who didn't fear retaliation those with "nothing to lose" could threaten the U.S. with such a weapon, supporters say.
Then-President Clinton last year deferred a decision on whether to build the national missile defense, leaving the final go-ahead to his successor.
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